24 Pioneer Labourers 



and washed away by the next shower. As for the 

 single carbonate of potash, it does not need even a 

 shower to help it, but melts away in the moisture of 

 the air, as anyone may know who has ever tried to keep 

 it wrapped in paper. 



The carbonates being thus removed, and the clayey 

 part of the felspar softened and washed away to form 

 beds of clay elsewhere, the crystals of quartz and mica 

 must needs fall apart, and so the work of breaking 

 down the rock goes on. 



But nature's labourers proceed upon the principle 

 that * union is strength,' and they so constantly work in 

 company that it is a difficult matter to apportion the 

 result of their labours exactly each to each. We have 

 already seen how water dissolves ; we must now look 

 at it in another capacity, and see how it acts the part 

 of crowbar and pickaxe, and even at times of dynamite. 

 A cubic inch of water, when converted into steam, 

 occupies just 1,728 times as much space as it did 

 before, and it expands with such violent force as to 

 shatter the rocks beneath which it is confined. Such 

 explosions as this sometimes occur during volcanic 

 eruptions, water having found its way down through the 

 earth till it has come into contact with some mass of 

 molten lava, which has converted it into steam, and 

 made it a powerful engine of destruction. 



But water expands also, though in a less degree, 

 when it is converted into ice, and it is under this aspect 

 that we are most famihar with its doings. Ice occupies 

 only one-fifteenth more space than the water from 

 which it is formed, and, compared with the expansion 

 which takes place in the formation of steam, this 

 increase may sound insignificant. But its effects are 



